Pitched roof insulation rolls

[SuperPav]

Just about to order our rolls of insulation for the pitched roof (vaulted ceilings) - approx 120sqm of roof surface to insulate at 200mm between rafters. There will also be 50mm PIR under rafters.

 

The plan originally was to use the ionic treated sheepwool. Main reasons are it's a natural material so (irrationally) we like the idea of it, and also the fact that it appears much better than rockwool or plastic at controlling moisture. As these will all be bed and bathrooms, and we have OSB sheathing over the top which has a somewhat unproven vapour transmission, the moisture control element seems like a good idea.

 

I've just run the £/sqm costings though and bloody hell have prices doubled since last year?! I didn't think sheep had any microchips in them?!

 

Sheepwool @200mm - £44/sqm

Thermafleece recycled PET @ 200mm - £15/sqm

Knauf earthwool 44 @200mm - £6/sqm !!!

 

At 100-120sqm that is a big difference!

 

As we'll be installing ourselves, I have already ruled out rockwool as done that enough times and simply cannot be dealing with the itchy mess, but can anybody hit me with some pros/cons of the options to make the decision.

[Russell griffiths]

I used knauf omni fit 100mm x 2 layers easier to handle and cut at 100mm. 

Are you happy with 50mm pir, I used 75mm and I’m still not happy. 

Taped all sheets together and glued them all while fitting for vapour control. 

[SuperPav]

We may still use 75mm in some areas, but it's a pitched roof down to a relatively low eaves upstairs, and don't want it to be below 2000mm internal height at the eaves so we're limited.

 

I think we've now decided to discount wool due to price, and will probably be going with recycled PET. 

The Mrs did suggest to go for cheap rockwool (as it'll be me installing it!!) and she'll buy me a gallon tub of barrier cream to help with the itchiness. I'm not sold on this proposal.

[Iceverge]

Have you considered blown in cellulose? 

[hb1982]

there is an acoustic benefit when using heavy rockwool insulation in pitch-roof construction.

 

[Thorfun]

2 hours ago, Iceverge said:

Have you considered blown in cellulose? 

+1 for this! I've just finished installing 190mm glass wool batts in the roof and I wish I'd got deeper trusses and used blown in cellulose. it's not a job I want to repeat.

 

don't worry about itchiness. just make sure you put overalls on and have a full face mask and you'll be fine.